Portable self-contained electrical cardiometric device with three fixed-position nonuniformly spaced input probes

ABSTRACT

A portable self-contained electrical cardiometric device employable for the quick monitoring and indicating of a heartproduced electrical signal in a person&#39;&#39;s body. The device includes three specially positioned electrical probes which are for electrically contacting a person&#39;&#39;s body to detect such a signal, a battery-powered electronic amplifier connected to these probes for amplifying a detected signal, and a suitable display or indicating unit for following the instantaneous amplitude of an amplified signal. The probes include fluid passages that communicate with a pump and a fluid reservoir in the device from which a conductive fluid may be ejected to enhance the electrical contact between the probes and a person&#39;&#39;s skin.

United States Patent [191 1-] 3,776,228 Semler 4, 1973 PORTABLESELF-CONTAINED 3,326,207 6/1967 Egan 128/206 E ELECTRICAL CARDIOMETRICDEVICE 3,380,445 4/1968 Frasier 128/206 E WITH THREE FxXED POSITION3,547,107 12/1970 Chapman et a] 128/206 A NONUNIFORMLY SPACED INPUTPROBES FOREIGN ATENTS 0R APPLICATIONS 76 Inventor; Herbert J Semler,2330 w 250,557 11/1966 Austria 128/206 R Flanders, Portland, Oreg. 97210Primary Examiner-William E. Kamm [22] Flled: Sept 1971 Attorney-Kolisch,Hartwell & Dickinson [21] Appl. No.: 181,862

Related US. Application Data US. Cl. 128/2.06 R, 128/206 E, 128/417,

[57] ABSTRACT A portable self-contained electrical cardiometric deviceemployable for the quick monitoring and indicating of a heart-producedelectrical signal in a persons body. The device includes three speciallypositioned 128/DIG 4 electrical probes which are for electricallycontacting 51 Int. Cl A6lb 5/04 a body detect Such a Signal, a battery-58 Field of Search 128 205 R, 2.05 T P electronic amplifier connected tothese 128/206 A 106 B 206 E, 206 F, 206 probes for amplifying a detectedsignal, and a suitable dis la or indicating unit for followin theinstanta- 2.1 E, 2.1 R,417, DIG.4 P y g neous amplitude of an amplifiedsignal. The probes in- [56] References Cited clude fluid passages thatcommunicate with a pump UNITED STATES PATENTS and a fluid reservoir inthe device from which a conductive fluid may be ejected to enhance theelectrical 5 Contact between the probes and a p s n 1 er 2,555,037 51951 Jensen 128/417 5 Claims, 8 Drawing Figures 2 .2 1 \l j I 32 I :11:X I 23 j 16 J 1 a M 24 3 i ll 4 h 1 u I \\\\\\1\\\\\ "AIFNIEHBEP, 4mm$776,228

sum 1 (IF 2 m az bl 52 I3 23 m I 16 I7 I6 HERBERT J. SEMLER I I7 5623 4234 INVENTOR 35 39 4| BY HM I! FIG. 2 m

PORTABLE SELF-CONTAINED ELECTRICAL CARDIOMETRIC DEVICE WITH THREEFIXED-POSITION NONUNIFORMLY SPACED INPUT PROBES CROSS REFERENCE TORELATED PRIOR-FILED APPLICATION This is a continuation of my nowabandoned priorfiled copending application, Ser. No. 36,065, filed May ll, 1970, entitled Portable Cardiac Monitor.

BACKGROUND AND SUMMARY OF TI-IE INVENTION This invention pertains to aportable self-contained i type just generally indicated. Emergencysituations arise constantly where it is desired, and necessary, toobtain immediate, on-the-spot, accurate information regarding a personsheart activity if prompt and proper treatment is to be given. Often,quickly obtained information of this type is what makes the differencebetween saving and losing a life.

Obviously, conventional, cumbersome cardiac monitoring equipment, whichis relatively nonportable, and which may require considerable warmup andsetup time, does not meet this need. i i

A general object of the present invention, therefore, is to provide anovel, portable self-contained electrical cardiometric device whichtakes care of the need expressed above in a practical and satisfactorymanner.

Another object of the invention is to provide such a device which caneasily be carried in a persons pocket or in a small travel case, readilyheld and operated by one hand, and which permits a substantiallyimmediate reading, or monitoring, of a persons heart activity.

More specifically, an object of the invention is to provide such adevice which reliably monitors an electrical signal produced by heartactivity in'a persons body, and which affords an accurate, and easilyreadable and interpretable, indication of such a signal.

A further object of the present invention is to provide a device of thetype so far generally described which features three novelfixed-position, nonuniformly spaced input probes that are speciallyoriented in the device to promote accurate detection of electricalsignals of the kind mentioned above.

According to a preferred embodiment of the invention, the proposedcardiometric device comprises a small elongated housing containing anelectronic amplifier, and a battery power source therefor. The housingis easily held in one hand. Connected to the amplifier are threefixed-position input probes, oriented as contemplated by the invention,and a suitable indicating device, such as a lamp, or a meter. The threeinput probes are arranged with two of them, which are designated hereinas positive and negative probes, no less than seven centimeters apart,and with the third probe, which is designated a ground probe, disposedcloser to the negative probe than to the positive probe. Preferably, theground probe is offset from a straight line extending between thepositive and negative probes.

DESCRIPTION OF THE DRAWINGS These and other objects and advantagesattained by the invention will become more fully apparent as thedescription which follows is read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a full scale top perspective view of a device constructedaccording to the present invention;

FIG. 2, on essentially the same scale as FIG. 1, is a top plan view,partially in section, of the device of FIG. 1, with a portion of ahousing in the device removed;

FIG. 3, on essentially the same scale as FIGS. 1 and 2, is a sectionalside elevation of the device of FIG. 1;

FIG. 4 is an enlarged vertical section of a probe employed in the deviceof FIGS. 1, 2 and 3;

FIG. 5 is an enlarged vertical section illustrating one type of aremovable foot which may be attached to a probe in the device;

FIG. 6 is a bottom view of the foot of FIG. 5;

FIG. 7 is an enlarged vertical section view illustrating another type ofremovable foot which may be attached to a probe; and

FIG. 8 is a time-base graph illustrating a typical PQRST voltage displayof a normally healthy persons heart activity.

DETAILED DESCRIPTION OF THE INVENTION Turning now to the drawings, andreferring first to FIGS. 1-3, indicated generally at 10in FIG. 1 is acardiometric device constructed according to the present invention.Device 10 includes an elongated two-part case, including a base 11 and acover 12. The base has a somewhat U-shaped transverse cross section, andwhen fitted together with cover 1.2 (as shown in FIG. 1), forms acompletely enclosed protective housing for various other parts in thedevice. Such a housing is relatively easy and inexpensive to fabricate.Preferably, its parts are made of a relatively lightweight metal, suchas aluminum.

Although it is appreciated that the precise outside dimensions of thehousing in device 10 may be made to suit different particularapplications, the housing shown herein preferably has a length of about6 to 7 inches, a width of about 2 to 2% inches, and a depth of about 1%inches. It will be apparent that with dimensions such as these, thedevice may easily be held in one hand, and can readily be carried in apersons pocket or in various forms of small travel cases, such as abriefcase.

In the embodiment of the invention being described, the cover and baseof the housing are releasably secured together by screws, such asexposed thumb screw 15, which are screwed into posts, such as post 13(see FIGS. 2 and 3). With such an arrangement, components inside thehousing (still to be described) are readily accessible for service andother purposes.

Suitably mounted on the underside of base 11 and protruding outwardlyfrom the base, are three signal input probes constructed and arranged ascontemplated herein. These three probes are designated by referencenumerals 16, 17, 18. For reasons which will be more fully explainedherein, probe 16 constitutes a positive probe, probe 17 constitutes aground probe, and probe 18 constitutes a negative probe. As will also bemore fully explained later on, these three probes are employed to makeelectrical contact with a persons skin, for the purpose of picking upthe usual electrical signal produced in the persons body by heartactivity.

The relative positioning and spacing of the probes has been found toconstitute an'important and critical factor in the devices ability toprovide accurate and easily interpretable information regarding heartactivity. More specifically, it has been discovered that for the highestpossible accuracy, the negative and positive probes should be spacedapart no less than seven centimeters, with the ground probe positionedmore closely to the negative probe than to the positive probe. Probepositionings and spacings differing from these criteria have been foundto produce inaccurate and poorly interpretable information. Particularlysatisfactory performance has been found to result with the probes spacedapart and oriented essentially as indicated in FIG. 2, which (asindicated above) is approximately a full scale view of a device 10. Inthis specific probe arrangement, it will be noted that ground probe 17is offset from a straight line extending between probes 16, 18. Further,it will be observed that the distance between probes 16, 17 is somewhatless than the distance between probes 16, 18.

Preferably, probes 16, 17, 18 are fabricated of, or plated with, asuitable highly electrically conductive material, such as silver ornickel. The probes have essentially the same constructions their lowerend portions being tapered as indicated. As can be seen clearly in FIG.4, which illustrates positive probe 16, the probes include axiallydisposed central, double-openended bores 22, the purpose for which willbe explained shortly. In their respective mountings on base 11, theprobes are insulated from electrical contact with the base by means ofinsulators 19 (see FIG. 4).

Referring for a moment to FIGS. and 6, illustrated therein is what mightbe thought of as a detachable contact foot 64 which is shown detachablymounted on probe 16. Similar feet may be provided for and mounted onprobes 17, 18. A foot 64 has the axial cross-sectional configurationclearly illustrated in FIG. 5, and includes a knurled bottom surface 65,and a central, axial, tapered bore 66 which joins axially with aconsiderably smaller bore 69 that opens to the base of the foot. Eactfoot 64 is adapted to be easily twisted onto and off of a probe, withthe tapered outside surface of the probe fitting snugly against thetapered inside wall of the bore 66 inside the foot. Preferably, feet 64are constructed from the same type material used in the probes.

Feet 64 may be used advantageously in various circumstances where it isdesired to maximize the contact area with a persons skin. It will beapparent that the knurled bottom surfaces of these feet facilitaterelatively large-area contact with skin.

Considering FIG. 7, this illustrates at 67 another type of foot whichmay be fitted (in a manner similar to that described for feet 64) onto aprobe. A foot 67 includes a substantially flat bottom face 70 from whichprojects a short central needle 68. This kind of a foot may be used onthe probes under circumstances where it is desired to make electricalcontact with a person through puncturing of his skin.

It will be noted that the two different types of feet which have justbeen described, do not appreciably change the relative positions andspacings of the points at which electrical contact is made with a persons skin. This is an important feature.

Considering now other components employed in device 10, and referringagain particularly to FIGS. 1-3, suitably mounted inside the housing area fluid supply system 25, and an electronic amplifier. or electricalcircuit means, 24. The fluid supply system is adapted to be used inconjunction with the central axial bores mentioned previously in theprobes, for the purpose of ejecting through these bores, and onto aperson s skin, a suitable conductive fluid, such as alcohol or water, toenhance the electrical contact between the probes and the skin.Accordingly, the fluid supply system includes a reservoir 27, adigitally operable pump 34, and three flexible tubes 32 which connectoutlets 31 in the reservoir with the interiors of the bores in theprobes. Access for filling and draining the reservoir is had through aninlet 29 which is exposed through housing cover 12.

Reservoir 27 preferably is made of a relatively thin flexible material,such as a pliable plastic material. Pump 34, which is used to ejectfluid from the reservoir, comprises an elongated arm 35 which is pivotedat 37 on housing base 11. An end portion 36 of the arm contacts a sideof the reservoir (as can be seen clearly in FIG. 2), and the arm carriesa push button 39 which extends freely through a bore 40 in base 11,outwardly of the housing.

With fluid stored in the reservoir, digital pressure by an operator uponbutton 39 forces end portion 36 of the arm against the reservoir,distorting the same and causing the ejection of fluid through theoutlets, tubes, and probes. A conventional air inlet valve 43 admits airto the reservoir to replace ejected fluid.

The ejecting of fluid through the probes to improve electrical contactwith a persons body is especially useful where it is desired toestablish such contact without removing clothing. In other words, byejecting fluid, the fluid wets the clothing and reaches the skin toestablish adequate electrical contact between the skin and the probes.

Amplifier 24 is a conventional three-input, high-gain,high-frequency-AC-isolation-type amplifier capable of responding torelatively low frequency electrical signals, such as those produced bythe heart. The amplifier includes the usual positive, negative andground input terminals (hidden from view in the drawings), and isadapted to detect a differential voltage between its positive andnegative terminals. Probes 16, 18, 17 are suitably conductivelyconnected to the amplifiers positive, negative and ground terminals,respectivelythus accounting for the reference made earlier to theseprobes as positive, negative and ground probes, respectively. Power forenergizing the amplifier is supplied by a battery 56 which is containedwithin the housing. A switch 58 mounted on base 11, and interposedelectrically between the amplifier and battery, is provided for turningthe amplifier on and off.

Details of the amplifier form no part of the present invention, and thusare not illustrated. Preferably, however, the amplifier is constructedusing modern semiconductor devices, thus enabling it to be relativelycompact, whereby it can easily fit into a housing having dimensions likethose described above, and permitting it to operate at relatively lowpower levels. In addition, there is preferablyprovided in the amplifier,interconnecting the three input terminals, a conventional diodeprotective circuit which protects the amplifier per se from any excessinput voltages (such as might occur during defibrillation of a patient),and which, more importantly, protects a patient against any possibleinternal malfunction of the amplifier that might accidentally place aharmful voltage between any two of its input terminals.

An output signal from the amplifier takes the form of anintensity-varying signal which follows intensity variations in thedifferential voltage appearing between its positive and negative inputterminals. In device 10, such an output signal is supplied both to anindicating lamp 51, which is mounted on cover 12, and also to aconventional output jack 57 mounted on base 11.

Referring now to H6. 8, the manner in which device may be used tomonitor a persons heart activity is explained. FIG. 8 is a time-basegraph illustrating typical PQRST voltage excursions which occur in anormally healthy persons body due to heart activity. In this type ofdisplay, various points in a single cycle refleeting heart activity aredesignated by the letters P, Q, R, S and T. Medical practitionersskilled in the art are fully familiar with such a graph.

With device 10 turned on, and with electrical contact establishedbetween probes 16, 17, 18 and a persons skin (typically on the personschest), the electrical voltage signal in the persons body is picked upby the probes, fed to amplifier 24, amplified therein, and then suppliedto lamp 51 and jack 57. Under such circumstances, the intensity of lightcoming from lamp 51 follows intensity changes in the output signal fromthe amplifier. Through experience in using the device, one can readilydetect in the flickering of the lamp all of the significant pointsP, Q,R, S and Tin a cycle of heart activity. As a consequence, and withlsuchexperience, a skilled medical practitioner can easily determine the thencondition of the persons heart.

With a device such as device 10 available, it will be obvious that animmediate on-thespot emergency diagnosis of a personsheart condition canbe made. If desired, lamp 51 may be replaced by a suitable meter whoseneedle tracks or follows the output signal of the amplifier. Further,and under circumstances permitting such operation, output jack 57 may beemployed to supply a signal to any desired external indicating device,such as a strip-chart recorder.

The novel positioning and spacing of the fixed probe employed in thedevice facilitate the obtaining of accurate information regarding heartactivity. This is especially important in making the device practicalfor use in emergency-type situations, where time must not be wasted insetting up to take measurements. Under different kinds of circumstances,and as dictated by user experience, the different kinds of probe-mountedfeet described above may be used, and/or the fluid system may beemployed, to enhance electrical contact with a persons body.

It is thus apparent that the proposed device adequately fills the needexpressed earlier herein. And, while a preferred embodiment of theinvention has been described, and certain modifications suggested, it isappreciated that other variations and modifications may be made withoutdeparting from the spirit of the invention.

It is claimed and desired to secure by Letters Patent:

1. In a selfcontained portable electrical cardiometric device includinga housing, electrical circuit means therein for processingheart-produced electrical signals including positive, negative andground input terminals for said signals, a power source for said circuitmeans, and indicator means coupled to said circuit means for indicatingheart activity,

means for electrically contacting a persons body and picking upheart-produced electrical signals therein, said means consisting ofthree electrically conductive probes, including a positive, a negativeand a ground probe each connected to a corresponding one of said inputterminals, mounted in spaced-apart fixed triangularly disposed positionson said housing,

said positive and negative probes being spaced apart by a distance of atleast seven centimeters, and said ground probe being disposed closer tothe negative probe than to the positive probe.

2. In a self-contained portable electrical cardiometric device includinga housing, electrical circuit means therein for processingheart-produced electrical signals, a power source for said circuitmeans, and indicator means coupled to said circuit means for indicatingheat activity,

means connected to said circuit means for electrically contacting apersons body and picking up heart-produced electrical signals therein,said means comprising three electrically conductive probes mounted inspaced-apart fixed triangularly disposed positions on said housing,

two of said probes being spaced apart by a distance of at least sevencentimeters, and the third probe being disposed closer to one of saidtwo probes than to the other probe, with the distance between said thirdand one probes being less than 7 centimeters.

3. The device of claim 2, wherein said electrical circuit means includespositive, negative and ground input terminals, said one probe isconnected to said negative terminal, said other probe is connected tosaid positive terminal, and said third probe is connected to said groundterminal.

4. In a self-contained portable electrical cardiometric device includinga housing, electrical circuit means therein for processingheart-produced electrical signals, a power source for said circuitmeans, and indicator means coupled to said circuit means for indicatingheart activity,

means connected to said circuit means for electrically contacting apersons body and picking up heart-produced electrical signals therein,said means consisting of three electrically conductive probes mounted inspaced-apart fixed triangularly disposed positions on said housing,

two of said probes being spaced apart by a distance of at least 7centimeters, and the third probe being disposed closer to one of saidtwo probes than to the other probe, with the distance between said thirdand other probes being less than the distance between said one and saidother probes.

5. The device of claim 4, wherein said electrical circuit means includespositive, negative and ground input terminals, said one probe isconnected to said negative terminal, said other probe is connected tosaid positive terminal, and said third probe is connected to said groundterminal.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 775.22 Dated December 4, 1973 Invent0r(S) Herbert J. Semler It is certifiedthat error appears in the above-identified patent 1 and that saidLetters Patent are hereby corrected as shown below:

Column 6 line 22, Claim 2, change "heat activity" to --heart activity-mSigned and sealed this lth day of A i 197M.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C MARSHALL DANN Attesting Officer Commissioner ofPatents USCOMMvDC 00:1 o-Peo FORM PO-IOSO (10-69) a 0.5. sovznnnim'"11mm; omcl Inn o-lu-a

1. In a self-contained portable electrical cardiometric device includinga housing, electrical circuit means therein for processingheart-produced electrical signals including positive, negative andground input terminals for said signals, a power source for said circuitmeans, and indicator means coupled to said circuit means for indicatingheart activity, means for electrically contacting a person''s body andpicking up heart-produced electrical signals therein, said meansconsisting of three electrically conductive probes, including apositive, a negative and a ground probe each connected to acorresponding one of said input terminals, mounted in spacedapart fixedtriangularly disposed positions on said housing, said positive andnegative probes being spaced apart by a distance of at least sevencentimeters, and said ground probe being disposed closer to the negativeprobe than to the positive probe.
 2. In a self-contained portableelectrical cardiometric device including a housing, electrical circuitmeans therein for processing heart-produced electrical signals, a powersource for said circuit means, and indicator means coupled to saidcircuit means for indicating heat activity, means connected to saidcircuit means for electrically contacting a person''s body and pickingup heart-produced electrical signals therein, said means comprisingthree electrically conductive probes mounted in spaced-apart fixedtriangularly disposed positions on said housing, two of said probesbeing spaced apart by a distance of at least seven centimeters, and thethird probe being disposed closer to one of said two probes than to theother probe, with the distance between saiD third and one probes beingless than 7 centimeters.
 3. The device of claim 2, wherein saidelectrical circuit means includes positive, negative and ground inputterminals, said one probe is connected to said negative terminal, saidother probe is connected to said positive terminal, and said third probeis connected to said ground terminal.
 4. In a self-contained portableelectrical cardiometric device including a housing, electrical circuitmeans therein for processing heart-produced electrical signals, a powersource for said circuit means, and indicator means coupled to saidcircuit means for indicating heart activity, means connected to saidcircuit means for electrically contacting a person''s body and pickingup heart-produced electrical signals therein, said means consisting ofthree electrically conductive probes mounted in spaced-apart fixedtriangularly disposed positions on said housing, two of said probesbeing spaced apart by a distance of at least 7 centimeters, and thethird probe being disposed closer to one of said two probes than to theother probe, with the distance between said third and other probes beingless than the distance between said one and said other probes.
 5. Thedevice of claim 4, wherein said electrical circuit means includespositive, negative and ground input terminals, said one probe isconnected to said negative terminal, said other probe is connected tosaid positive terminal, and said third probe is connected to said groundterminal.